Share-based Compensation and Employee Benefits - Schedule of One-Percentage Point Change in Assumed Health Care Cost Trends (Details) - OPEB - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
One-percentage point increase:
Aggregate of service cost and interest cost	$ 1	$ 1
Accumulated postretirement benefit obligation	14	16
One-percentage point decrease:
Aggregate of service cost and interest cost	0	(1)
Accumulated postretirement benefit obligation	$ (12)	$ (14)

Defined Benefit Plan, Effect Of One-Percentage Point Decrease In Assumed Health Care Cost Trend Rate

No definition available.

Name:	kmi_DefinedBenefitPlanEffectOfOnePercentagePointDecreaseInAssumedHealthCareCostTrendRateAbstract
Namespace Prefix:	kmi_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Defined Benefit Plan, Effect Of One-Percentage Point Increase In Assumed Health Care Cost Trend Rate

+ References

No definition available.

+ Details

Name:	kmi_DefinedBenefitPlanEffectOfOnePercentagePointIncreaseInAssumedHealthCareCostTrendRateAbstract
Namespace Prefix:	kmi_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of decrease in accumulated postretirement benefit obligation from one-percentage-point decrease in assumed health care cost trend rate.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (m)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointDecreaseOnAccumulatedPostretirementBenefitObligation1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of decrease in service and interest cost components of net periodic postretirement benefit cost from one-percentage-point decrease in assumed health care cost trend rate.

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointDecreaseOnServiceAndInterestCostComponents1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of increase in accumulated postretirement benefit obligation from one-percentage-point increase in assumed health care cost trend rate.

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointIncreaseOnAccumulatedPostretirementBenefitObligation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of increase in service and interest cost components of net periodic postretirement benefit cost from one-percentage-point increase in assumed health care cost trend rate.

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanEffectOfOnePercentagePointIncreaseOnServiceAndInterestCostComponents
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_RetirementPlanTypeAxis=us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: